Conventional single strike ignition systems for producing a combustion arc across electrodes of a spark plug disposed within a combustion chamber are well known. The predominant application for such systems is timed combustion of a compressed fuel charge in a combustion cylinder of an internal combustion engine. Ignition systems conventionally employ an ignition coil which provides an auto-transformer function to generate a high voltage across the electrodes of a spark plug sufficient to result in the desired combustion arc. Known ignition systems may employ a single ignition coil with mechanical or electronic distribution of the high voltage sequentially to multiple spark plugs in a multi-cylinder engine. So called distributorless concurrent discharge ignition systems are known in which pairs of combustion cylinders share a single ignition coil and its high-voltage output. The one of the cylinders undergoing compression of a fuel charge is said to receive a combustion spark while the other of the cylinders undergoing exhaust of gases is said to receive a waste spark. Another known variety of distributorless ignition systems is may be referred to as a coil at plug or coil near plug. As the name suggests, the coil at plug systems have a coil associated with each cylinder of a multi-cylinder internal combustion engine and are characterized by packaging challenges due to the desired proximal placement of the ignition coil to the spark plug.
Generally, desirable objectives of any internal combustion engine ignition system is to maximize the energy delivered across the electrode gaps of the spark plugs and to increase the time of the discharge or burn time. Such an objective has the benefit of extending the combustion process for more complete burn. However, the relationship between energy delivered and ignition coil size is generally one of direct correspondence. Increase in ignition coil size is generally disadvantageous or impractical since mass is likely to also increase as is packaging difficulty particularly with respect to distributed ignition systems and most notably with respect to coil at plug systems in which available space for the coils is significantly limited.
Another shortfall of high burn time ignition coils in general relates to the turns ratio of the secondary to primary winding. Typically, high burn time ignition coils require a relatively high turns ratio. This may be problematic as a breakdown voltage induced across the secondary winding, and hence across the gapped electrodes, may be reached at the beginning of the primary charging prior to the desired ignition timing. Early breakdown voltages yield undesirable premature light-off of the fuel charge or, alternatively stated, ignition on make. Additional secondary winding circuitry in the form of expensive high-voltage blocking diodes are therefore commonly introduced to block ignition on make in high turns ratio ignition coils.
AC ignition systems are also known for providing extended burn benefits but typically employ expensive DC-DC converters at the input to raise the input voltage to a level providing adequate performance of the ignition coil in both transformer and induction modes. Additionally, and consistent with size and mass minimization objectives, high switching frequency DC-DC converters are used which may produce undesirably high levels of radio frequency (RF) interference.
Dual strike ignition systems are also known for producing a first combustion arc across electrodes of a spark plug disposed within a combustion cylinder followed by a second arc across the electrodes. The second arc may be characterized as a secondary combustion arc when used for the purpose of extending the burn, or may be characterized as a measurement arc when used for the purpose of detecting misfire in conjunction with a plasma induced misfire detection system. Co-pending U.S. patent application Ser. Nos. 08/651,416 and 08/651,320 also assigned to the Assignee of the present invention disclose an exemplary dual strike ignition system and plasma induced misfire detection system. Such exemplary systems, while providing improvements to the art, may require high turns ratios subject to ignition on make events. Additionally, such systems provide for discontinuous or piecemeal introduction of energy into the ignition process.